Pulp screen



Aug. 22, 1944- D WELLS 2,356,289

PULP SCREEN Filed Feb. 17, 1942 2 Sheets-Sheet 1 mvzu on;

ATTORNEYS 1944- H; D. WELLS 2,356,289

PULP SCREEN Filed Feb. 17, 1942 2 Sheets-Sheet 2 oao ooooo 53 H m Z25 5 i v INVENTOR 4 I i aeaflzwva il ATTORNEYS Patented Aug. 22, 1944 UNITED STATES PATENT OFFICE PULP SCREEN Harold Donald Wells, Glens Falls, N. Y. Appllcation' February 11,1942, Serial No. 431,315

2 Claims.

This invention relates to a pulp screen and has for an object to provide a device of this character which will handle a w d variety of pulp, such as paper stock and other pulp, and will produce a cleaner quality of pulp than other screens by combining in one machin a screen,'

centrifugal separation basket, and a screening impeller. I

A further object is to provide a device of this character in which the cleaned pulp is floated upward and discharged from the machine, while the tailings are rejected and removed from the bottom of the machine where they settle after bein D ec piated from the pulp.

A further object is to provide a device of this character which will be formed of a few strong, simple and durable parts, which will be inexpensive to manufacture, and which will not easily get out of order.

With the above and other objects in view, the invention consists of certain novel details of construction and combination 'of parts hereinafter fully described and claimed, it being understood that various modifications may be resorted to within the scope of the appended claims without departing from the spirit or sacrificing any of the advantages of the invention.

In the accompanying drawings forming a part of this specification:

Figure 1 is a. plan view of a pulp screen con structed in accordance with the invention.

Figure 2 is a vertical sectional view of the pulp screen taken on the line 2 -2 of Figure 1.

Figure 3 is a cross sectional view of the pulp screen taken on the line 3-3 of Figure 2.

Figure 4 is a detail cross sectional view taken on the line 4-1 of Figure 2, showing the vanes or the separation basket and of the'screening impeller.

Figure 5' is a detail cross sectional view taken on the line 55 of Figure 3, showing the tailing control box.

Referring now to the drawings in which like characters of reference designate similar parts in the various views, the pulp screen comprises a vertically disposed cylindrical casing I0 which is supported upon a. base H and upon which is also supported an electric motor II. The casing is provided at the upper end with an inwardly extending annular flange l3, and dis, posed within the lower end of the casing is a funnel shaped bottom l4 through which tailings escape to a pipe IS. A water pipe l6 enters the casing below the bottom and communicates with the spout ll of the bottom for supplying water to clean the pulp and float the pulp to the top of the casing.

A cylindrical screen I8 is disposed concentrically within the casing. The screen is secured to a frame comprising spaced vertically disposed bars l9, and superposed rings 20 secured to the bars. 2| and an imperforate top 22 to which a pulp discharge pipe 23 is connected. The frame bars l9 are integral at the top with a flange 24 which is superposed upon the flange l3 at the top of the casing and is fixedly secured thereto by screw bolts 25, or other connectors.

A vertically disposed shaft 26 is rotatably mounted at the lower end in a stuffing box bearing 21 carried by the top of the base II and at the upper end is rotatably mounted in a bearing 28 carried by the top 22 of the screen. The shaft is disposed coaxial with the screen and is driven by a belt drive 29 disposed in the base H and connected to the shaft 30 of the electric motor l2.

Keyed to the shaft 26, as shown at .3l, see Figure 2, is the driving disk 32 of an-impeller. The impeller comprises a bottom ring 33 which is bolted to the disk, as shown at 34. A plurality of vanes 35 extend upwardly from the ring 33 and are reinforced at intervals by spaced superposed rings 36. The uppermost reinforcing ring 36 is disposed at the top of the cylindrical screen |8.' A cylindrical separation basket 31, formed preferably of imperforate sheet metal, is disposed outside of and concentric with the impeller. The separation basket is suspended at the top from the impeller by a ring 31a which is fixed to the uppermost reinforcing ring 36 of the impeller, in any preferred manner, and is provided with outlet openings 39. The separation basket is open at the bottom.

A plurality of substantially triangular vanes 38 are secured longitudinally to the outer face of the separation basket at the bottom thereof. These vanes are disposed radially with respect to the separation basket, while, see Figure 3, the vanes 35 of the impeller are inclined at an angle of'about 45 to the impeller and thus have a. predetermined pitch.

In operation, the impeller and the separation baske? are rapidly rotated as a unit, while the pulp to be cleaned continuously flows into the casing Ill through a volute 40. The rotating impeller and separation basket starts the pulp swirling in the direction in which the impeller and separation basket are rotating, the motion of the pulp being accelerated by the vanes 35 of The frame has an imperforate bottom the impeller and 38 of the separation basket. This swirling motion at high velocity causes the dirt, saw dust, slivers and other foreign matter to centrifugally separate and gravitate onto the bottom M of the casing and passout through the discharge pipe W. The dilution water entering through the pipe it floats the paper making fiber out of the rejected tailings. The liquid and all sufiiciently fine particles of pulp pass through the screen l8, as indicated by the arrowheads H, see Figure 2, and are discharged from the screen through the outlet pipe 23 at the top of the screen. a

The impeller vanes 35 prevent coarse material from adhering to the periphery of the screen l8 and clogging the screen, and the'pitch of these vanes tend to throw the pulp centrifugally thus further aiding in keeping the screen clean. Moreover; when any impeller vane 35 passes a given point, the liquid pulp which was previously thrown out by said vane, immediately returns toward the screen, so that an oscillatory or reciprocatory motion is constantly given to the liquid pulp in a direction radially of the screen, thereby further aiding in the screening action and assisting in preventing clogging of the screen.

The rejected tailings pass upward through the pipe i into a tailing control box 42 having an adjustable gate 43 therein over which the tailings pass downward into a waste pipe 44, see Figure 5.

Since the operation of the parts has been described as the description of the parts progressed,

it is thought the invention. will be fully understood without further explanation.

What is claimed is:

1. A pulp screen comprising, a vertically disposed casing, a. stationary cylindrical screen in the casing closed at the top and at the bottom, a tape communicating with a side or the casing for conducting material into the casing, a pipe communicating with the top of the screen for conducting material from the screen, an impeller disposed concentric with the screen having vertical vanes of predetermined pitch disposed exteriorly oi the screen, a separating basket surrounding and spaced slightly from the impeller having vertical vanes extending radially toward the casing, the lower and upper ends of the annular space between the impeller and the centriiugal separating basket being open, and means for rotating the impeller and separating basket 2. A pulp screen comprising, a vertically dis posed casing having a funnel shaped bottom, a liquid pipe entering the bottom for supplying v liquid to the casing, a tailings pipe entering the bottom for conducting tailings from the casing, a shaft extending vertically in the casing, a. stationary cylindrical screen concentric with the shaft in the casing, a pipe communicating with a side of the casing for conducting material into the casing radially of the screen, a pipe com-1 municating with the top of the screen for conducting material from the screen, a skeleton impeller disposed concentric with the screen having pitch vanes disposed exteriorly of the screen for cleaning the screen and causing centrifugal motion of the contents of the casing, a separating basket surrounding and spaced slightly from the impeller having vertical vanes extending radially toward the casing, a disk fixed to the shaft and connected to the impeller and to the basket at the lower ends thereof Iorrotating the im peller and basket as a unit, and means ior rotating the shaft.

- I HAROLD DONALD WELLS. 

